import {
  ChangeDetectionStrategy,
  Component,
  EventEmitter,
  Input, OnInit,
  Output,
  ViewEncapsulation
} from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { Observable } from 'rxjs/Observable';
import { distinctUntilChanged, map } from 'rxjs/operators';

import { SortDirection, SortOptions } from '../../core/cache/models/sort-options.model';
import { PaginatedList } from '../../core/data/paginated-list';

import { RemoteData } from '../../core/data/remote-data';
import { fadeIn } from '../animations/fade';
import { hasNoValue, hasValue } from '../empty.util';
import { HostWindowService, WidthCategory } from '../host-window.service';
import { ListableObject } from '../object-collection/shared/listable-object.model';

import { PaginationComponentOptions } from '../pagination/pagination-component-options.model';

@Component({
  changeDetection: ChangeDetectionStrategy.Default,
  encapsulation: ViewEncapsulation.Emulated,
  selector: 'ds-object-grid',
  styleUrls: [ './object-grid.component.scss' ],
  templateUrl: './object-grid.component.html',
  animations: [fadeIn]
})

export class ObjectGridComponent implements OnInit {

  @Input() config: PaginationComponentOptions;
  @Input() sortConfig: SortOptions;
  @Input() hideGear = false;
  @Input() hidePagerWhenSinglePage = true;
  private _objects$: BehaviorSubject<RemoteData<PaginatedList<ListableObject>>>;
  @Input() set objects(objects: RemoteData<PaginatedList<ListableObject>>) {
    this._objects$.next(objects);
  }
  get objects() {
    return this._objects$.getValue();
  }

  /**
   * An event fired when the page is changed.
   * Event's payload equals to the newly selected page.
   */
  @Output() change: EventEmitter<{
    pagination: PaginationComponentOptions,
    sort: SortOptions
  }> = new EventEmitter<{
    pagination: PaginationComponentOptions,
    sort: SortOptions
  }>();

  /**
   * An event fired when the page is changed.
   * Event's payload equals to the newly selected page.
   */
  @Output() pageChange: EventEmitter<number> = new EventEmitter<number>();

  /**
   * An event fired when the page wsize is changed.
   * Event's payload equals to the newly selected page size.
   */
  @Output() pageSizeChange: EventEmitter<number> = new EventEmitter<number>();

  /**
   * An event fired when the sort direction is changed.
   * Event's payload equals to the newly selected sort direction.
   */
  @Output() sortDirectionChange: EventEmitter<SortDirection> = new EventEmitter<SortDirection>();

  @Output() paginationChange: EventEmitter<SortDirection> = new EventEmitter<any>();

  /**
   * An event fired when the sort field is changed.
   * Event's payload equals to the newly selected sort field.
   */
  @Output() sortFieldChange: EventEmitter<string> = new EventEmitter<string>();
  data: any = {};
  columns$: Observable<ListableObject[]>

  constructor(private hostWindow: HostWindowService) {
    this._objects$ = new BehaviorSubject(undefined);
  }

  ngOnInit(): void {
    const nbColumns$ = this.hostWindow.widthCategory.pipe(
      map((widthCat: WidthCategory) => {
        switch (widthCat) {
          case WidthCategory.XL:
          case WidthCategory.LG: {
            return 3;
          }
          case WidthCategory.MD:
          case WidthCategory.SM: {
            return 2;
          }
          default: {
            return 1;
          }
        }
      }),
      distinctUntilChanged()
    ).startWith(3);

    this.columns$ = Observable.combineLatest(
      nbColumns$,
      this._objects$,
      (nbColumns, objects) => {
        if (hasValue(objects) && hasValue(objects.payload) && hasValue(objects.payload.page)) {
          const page = objects.payload.page;

          const result = [];

          page.forEach((obj: ListableObject, i: number) => {
            const colNb = i % nbColumns;
            let col = result[colNb];
            if (hasNoValue(col)) {
              col = [];
            }
            result[colNb] = [...col, obj];
          });
          return result;
        } else {
          return [];
        }
    });
  }

  onPageChange(event) {
    this.pageChange.emit(event);
  }

  onPageSizeChange(event) {
    this.pageSizeChange.emit(event);
  }

  onSortDirectionChange(event) {
    this.sortDirectionChange.emit(event);
  }

  onSortFieldChange(event) {
    this.sortFieldChange.emit(event);
  }

  onPaginationChange(event) {
    this.paginationChange.emit(event);
  }

}